A major aspect of routing protocols is to ensure stability and robustness of a network even when subjected to unexpected events or an erroneous environment. As routing processes heavily depend on updates from the network to make routing decisions, protection of the process with error handling capabilities is important. Routing protocols are structured based on state machines which decide a next state in response to an event. If an unexpected event occurs, a well-structured routing protocol should be able to take necessary steps either to proceed to a known state or to remain in a current state in order to avoid undesirable results such as a network collapse.
Currently, conformance tests are performed for routing protocol validation and qualification. The conformance tests establish acceptance rules that govern correct routing behaviors, such as routing message exchanges in terms of message syntax, semantics, and protocol state transition. Conformance tests are capable of determining correct or expected routing behaviors of packet network elements. However, some field network failures are caused by some exceptions that are not covered by existing conformance testing methods.
U.S. Pat. No. 5,027,343 to Chan et al. discloses a remote test access system for Integrated Services Digital Network (ISDN) testing. A provision of the system is the ability to propagate frame check sequence (FCS) errors, residual bit errors, abort sequences and physical layer failures which are intentionally generated by conformance test suites.
U.S. Pat. No. 5,805,571 to Zwan et al. discloses a dynamic communication line analyzer apparatus and method. The apparatus includes error generation and insertion in protocols to permit dynamic error testing. An analyzer provides the error insertion capability by generating data errors, cyclic redundancy check (CRC) errors, frame errors and bipolar violation errors. Each of the errors may be generated either as single errors or at a specified error rate subject to processor control.
U.S. Pat. No. 6,069,873 to Pugaczewski et al. discloses closed-loop automated testing of system equipment and management. A set of tests are generated which inject predetermined errors into a tested device to test for compliance with protocol standards.
U.S. Pat. No. 6,373,822 B1 to Raj et al. discloses a data network protocol conformance testing system. The protocol conformance testing system creates negative protocol testing conditions with abnormal state packet sequences or packets with erroneous or invalid fields that relate to state transition. Also, protocol data structure testing is performed by sending fields of packets containing data values at upper and lower limits as dictated by specifications. Extreme and out-of-bound values are also sent in the packets and the responses of a unit-under-test are verified.
In general, passing any of the currently-available conformance tests does not necessarily guarantee that the network will be reliable under all failure conditions. Network outages due to routing protocol failures in live networks often involve unexpected or previously unknown triggering causes that are not covered in existing conformance testing methods and systems.